This application claims the priority of German application 198 40 841.2, filed in Germany on Sep. 7, 1998, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a heat-insulating cup having an inner and an outer sleeve, which is supported against an upper and a lower area of the inner sleeve, the outer sleeve otherwise surrounding an annular space, as well as comprising a joint bottom arranged at the inner sleeve and the outer sleeve.
A cup of this type is prior art in U.S. Pat. No. 5,685,480. The conical outer sleeve is somewhat folded inwards at its upper and lower end, so that it is supported at these two points on the also conical inner sleeve. The annular space between the inner sleeve and the outer sleeve is filled out with corrugated cardboard, which alternatively adheres to the inner sleeve and to the outer sleeve. This is to provide, in addition to the insulating effect, stability for the cup.
It is an object of the present invention to create a stable, heat-insulating cup, which is less complicated to produce.
This object has been achieved in accordance with the present invention in that the inner sleeve has a sudden widening in its upper area, on top of which widening the outer sleeve is disposed.
By means of this arrangement according to the present invention, the heat-insulating cup becomes sufficiently stable so that the annular space between the inner sleeve and the outer sleeve can advantageously remain free of any additional elements. As a result of the outer sleeve being supported on the widening of the inner sleeve, the conicity of the outer sleeve is as a rule more pointed than the conicity of the inner sleeve, and the annular space also becomes wider in the upper area of the cup. In this way, the stability of the inner sleeve with its contents cannot be impaired, even when the outer sleeve is pressed inwards when the cup is held. An important advantage thereof is that a heat-insulating cup of this kind can be produced very easily.
The widening in the upper area of the inner sleeve is as large as is achievable in the case of cardboard. The widening lies in the range of maximum 1 mm.
In an embodiment of the present invention it is provided that the outer sleeve with its lower end is folded around the lower end of the inner sleeve and also around a rim of the bottom. This permits an optically better finish towards the bottom.
The supporting of the outer sleeve on the inner sleeve in the lower area can take place directly or indirectly. Advantageously, a small intermediary layer is formed in the lower area of the inner sleeve, which intermediary layer ensures a minimum distance between the outer sleeve and the inner sleeve in the area of the bottom. For example, in one embodiment of the present invention, the lower end of the inner sleeve in the area of the bottom can be folded outwards, so that the wall thickness of the inner sleeve ensures the desired distance. In the case of another embodiment of the present invention, the bottom can be rolled outwards around the lower end of the inner sleeve, so that the thickness of the bottom ensures the desired distance between the inner sleeve and the outer sleeve. In any case, the outer sleeve is supported against the inner sleeve in the lower area of the cup by means of the above mentioned intermediary layer. In the upper area of the cup, however, the outer sleeve is disposed directly on the widening of the inner sleeve.
The upper area of the cup can have various designs. In one embodiment according to the present invention, the upper ends of the inner sleeve and the outer sleeve are rolled in together, for example to a round or flat pressed lip. In another embodiment of the present invention, the upper end of the unrolled outer sleeve is clamped in the rolled up upper end of the inner sleeve.
At the affixing points between the outer and inner sleeve or between the outer sleeve and the bottom, a sealing or a pressing can be provided. Alternatively, adhering by means of a glue application is also possible.